Airfoil variable cambering device and method

• US 4,247,066 A
• Filed: 02/21/1978
• Issued: 01/27/1981
• Est. Priority Date: 02/21/1978
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: General Dynamics Corporation
• Inventors: McAnally, Robert W., Gomez, Eduardo W., Frost, Richard C.
• Primary Examiner(s): Kelmachter, Barry L.
• Application Number:
  US05/879,650
• Time in Patent Office: 1,071 Days
• Field of Search: 244/219, 244/214, 244/218, 244/87, 244/53 B
• US Class Current: 244/219
• CPC Class Codes: B64C 3/48 by relatively-movable parts of wing structures
• CPC Class Codes: Y02T 50/10 Drag reduction

Abstract

Airfoil device and method providing smooth, continuous, variation in airfoil camber and surface curvature over substantially the entire length of the device by use of a trusslike bendable beam as an airfoil rib having the airfoil skin surfaces flexibly slidable relative thereto. The beam is divided chordwise into upper and lower beam members each formed of a plurality of articulated sections. The beam members are connected by a bendable jackscrew which upon rotation causes one member to move chordwise, and its curvature to be changed, relative to the other thereby effecting deflection of the airfoil with concomitant variation in its camber and the curvatures of its outer skin surfaces.

Claims

1. An airfoil variable cambering device for varying the camber and the outer surface curvature of an airfoil in a smooth, continuous fashion over substantially the entirety thereof which comprises:

airfoil rib means positioned in the airfoil for giving structural support thereto,

outer directed portions of the rib means approximately defining a major portion of the airfoil cross section;

airfoil outer skin means arranged over said outer directed portions of said rib means to form substantially smoothly continuous outer surfaces for the airfoil;

means connecting said skin means to said rib means;

the rib means being formed as a bendable beam divided into first and second beam members each extending substantially the length of the beam;

said beam members being positionally movable chordwise one with respect to the other so as to alter the beam contour; and

jackscrew means connecting said first and second beam members and rotatable to effect said chordwise movement of said beam members one with respect to the other;

whereby rotation of the jackscrew means causes one of said beam members to be positionally shifted relative to the other beam member to provide a smooth continuous variation in the camber of the airfoil and the curvature of its outer surface.

2. The variable cambering device of claim 1 in which said airfoil skin means is connected with said bendable rib means to freely and flexibly slide thereover.

3. The variable cambering device of claim 2 in which said skin means over said rib means is slidable relative thereto over substantially the full chordwise extent of the rib means.

4. The variable cambering device of claim 1 in which the mean lines of curvature of said first and second beam members are variable one with respect to the other.

5. The variable cambering device of claim 1 in which said beam members are respectively hinged to and pivotable about axes at opposite outer surface areas of the airfoil.

6. The device of claim 1 in which chord segments of one of said beam members are arranged generally opposite chord segments of the other beam member and positionally movable relative thereto to form generally opposed pairs of segments, each pair together forming a truss bay portion of the beam substantially the full height thereof, the geometry of said truss bay portion being variable by shifting the position of one of said segments with respect to the other of said segments whereby to lengthen or shorten the length of a diagonal of said truss bay portion.

7. The variable cambering device of claim 6 in which the extent of said positional shifting is variable as between pairs of said oppositely positioned chord segments.

8. The variable cambering device of claim 1 in which means are provided for turning said jackscrew means in both forward and reverse directions.

9. The variable cambering device of claim 1 in which said jackscrew means comprises a jackscrew shaft having a plurality of spaced apart threaded shaft sections serially flexibly connected along the axis of the shaft, the pitch of the threads varying as between at least two of said shaft sections.

10. The variable cambering device of claim 9 in which there are three of said threaded shaft sections, the threads thereof respectively varying in pitch by a ratio of 1:

2;

3.

11. The variable cambering device of claim 9 in which at least one of said threaded shaft sections is movable generally chordwise with respect to another of said threaded shafts along the axis of said jackscrew means.

12. The variable cambering device of claim 1 in which said jackscrew means connects said relatively movable beam members along approximately the longitudinal neutral axis of said beam.

13. An airfoil structure having means therein for varying the camber and outer surface curvatures thereof in a smooth continuous fashion which comprises:

airfoil rib means;

airfoil outer skin means arranged thereover said rib means and said outer skin means together forming an airfoil;

outer directed portions of the rib means approximately defining a substantial portion of said airfoil cross section with said skin means slidably connected over said rib means

the rib means being formed as a bendable beam divided into first and second beam members each extending substantially the length of the beam;

said beam members being positionally movable chordwise one with respect to the other so as to alter the beam contour; and

jackscrew means connecting said first and second beam members and rotatable to effect said chordwise movement of said beam members one with respect to the other;

whereby rotation of the jackscrew means causes one of said beam members to be positionally shifted relative to the other beam member to provide a smooth continuous variation in the camber of the airfoil and the curvature of its outer surface.

14. The airfoil of claim 13 in which a plurality of said rib means are positioned in the airfoil spanwise thereof.

15. The airfoil of claim 13 in which said airfoil forms a substantial portion of an aerodynamic lifting body.

16. The airfoil of claim 13 in which said airfoil forms the trailing edge portion of an aerodynamic lifting body.

17. The airfoil of claim 15 in which said lifting body is an aircraft wing.

18. The airfoil of claim 13 in which the airfoil is a portion of an aircraft empennage.

19. The airfoil of claim 13 in which the airfoil forms a portion of a jet engine exhaust nozzle.

20. The airfoil of claim 13 in which the airfoil forms a portion of an aircraft jet engine air intake.

21. The airfoil of claim 13 in which there are a plurality of said variable cambering means spanwise of said airfoil, at least one of said variable cambering means being bendable to greater or lesser degrees than at least one other of said variable cambering means whereby to impart a spanwise twist along said airfoil.

22. Method for varying the camber of an airfoil to produce smooth continuous variations in curvature both of the camber and the airfoil outer surfaces comprising:

providing a chordwise rib means as support for an airfoil outer surface in the form of a bendable beam divided into first and second beam members extending substantially the length of the beam;

each beam member having a plurality of trusslike chord segments hinged together to provide for flexure in each of said beam members and each beam member positionally shiftable generally chordwise one with respect to the other along their lengths,

said first and second beam members being connected together by a flexibly rotatable jackscrew means;

turning said jackscrew means, and

repositioning one of said beam members generally chordwise with respect to the other beam member to alter the position and curvature of one beam member with respect to the other beam member to effect a change in beam contour;

whereby the camber and exterior surface curvature of the airfoil are smoothly and continuously variable from previous to new positions and contours.

23. The method of claim 22 in which said airfoil outer surface is a skin means slidable with respect to said rib means and said repositioning of one of said beam members with respect to the other is simultaneous with the sliding of said skin means relative to outer directed portions of said rib means.

24. The method of claim 22 in which chord segments of one of said beam members are arranged generally opposite chord segments of the other beam member and positionally movable relative thereto to form generally opposed pairs of segments, each pair together forming a truss bay portion of the beam substantially the full height thereof, and said repositioning of one of said beam members with respect to the other beam member is accomplished by shifting one of the segments of at least one such pair generally chordwise relative to the other segment thereof so as to lengthen or shorten a diagonal of said truss bay portion between the cap portions of said beam.

25. The method of claim 24 in which said generally chordwise positional movement between the chord segments of a segment pair is variable.

26. The method of claim 24 in which said chordwise positional movement between the chord segments of a pair is variable relative to the positional movement between segments of another said segment pair.

27. The method of claim 22 in which a plurality of said bendable beam rib means are positioned spanwise of the airfoil and the camber of the airfoil is varied along the spanwise length by varying the bending of at least one of said rib means to a greater or lesser degree than at least one other of said rib means.